/Engine/Source/Runtime/Engine/Public/RawIndexBuffer.h
Retrieves an array view in to the index buffer. The array view allows code to retrieve indices as 32-bit regardless of how they are stored internally without a copy. The array view is valid only if: The buffer was created with NeedsCPUAccess = true OR the resource has not yet been initialized AND SetIndices has not been called since.
[FIndexArrayView](API\Runtime\Engine\FIndexArrayView) GetArrayView() const